The present invention relates to a color negative inspection apparatus for displaying a negative image of a color negative film as different color positive images through simulation for color and density correction in order to determine printing exposure conditions.
An color printing apparatus incorporates therein an automatic exposure control system by which at least one characteristic value of a color negative image is measured to determine printing exposures for three colors; namely red, green and blue, by using an exposure calculation formula including the characteristic value for each color. Actually, exposure control values are calculated for the three colors in place of the printing exposures to automatically control three color components of printing light. Because of color negatives including various scenes, the automatic exposure system is not always suitable for all such color originals to make well-finished prints. For this reason, a color negative inspection apparatus is necessarily used prior to actual printing to correctively determine proper printing exposures on unusual negatives from which well-finished color prints can not be reproduced by the automatic exposure control system. The correction of exposure is usually effected based on the experiences of an operator prior to printing.
As color original inspection apparatus for determining proper printing exposures, there is heretofore well known in the art an apparatus which display on a CRT display screen a color positive image simulated as a finished print image for a standardized printing exposure condition from an negative image of an color original taken by a color TV camera. Because the conventional color original inspection apparatus can display an simulated image to be actually printed by a color printing apparatus prior to actual printing, an improved fraction defective of finished prints is possibly effected with the aid of the color original inspection apparatus. If in fact the operator determines that an color negative image being inspected is improper to make an well-finished print under the standardized printing condition while observing an color positive image simulated and displayed on the CRT screen, the operator enters correction values into the color negative inspection apparatus through function keys such as a color correction keys, color density correction keys and so forth so as to display a color positive image through simulation for the color correction and/or the density correction.
In general, different manufacturers supply color printing apparatus provided with different exposure control systems. For example, Japanese Patent Publication No. 59-13,011 teaches some of these exposure control systems; one of which controls exposures for three colors based on only a large area transmittance density (LATD); the other based on the difference between a LATD value and a gradation difference. Because the above-mentioned color original inspection apparatus is adapted to display an image through simulation for the LATD exposure control, it is not available for printing apparatus provided with exposure control systems different from the LATD exposure control system in order to display a properly simulated image on the CRT screen.